Why is human eye sensitive to changes in brightness?


Have you ever experienced a sudden darkness in front of your eyes when you come back inside your home on a sunny day? Human eyes experience such phenomenon when we enter from a bright lighting to dim one. Even in opposite situations when we travel from inside of a tunnel to outside, there is a split second of darkness. We try to find out the reason behind the sensitivity of our eyes.

I recently did some search on the topic and found that the reason behind the phenomenon is pretty intriguing.
Little background:Our eyes are made up of two kinds of photoreceptor, called rods and cones. Rods are responsible for processing light when photons are scarce. Cones require more photons to fire and help us see in bright environment.
Main Reason: The rods are very sensitive to photons. Researchers say that single photon is enough to fire rods. The…

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